Rod cGMP-Phosphodiesterase γ-Subunit: Structure-Function Relationships
Cyclic GMP-phosphodiesterase (PDE) is the effector enzyme of vertebrate photoreceptor cells that regulates the level of the second messenger, cyclic GMP. PDE consists of catalytic Pαβ subunits and two inhibitory Pγ subunits. The Pγ subunits keep the enzymes activity low in the dark. Upon light activation of photoreceptor cells, the GTP-bound α-subunit of the rod G protein transducin (αt*) interacts with Pγ(s) and activates PDE. Thus, Pγ is involved in a series of protein-protein interactions, and the dynamics of these interactions are critical for the control of phototransduction. We have extensively examined the role of various regions of Pγ, the amino-terminal, the central cationic, and the carboxyl-terminal regions, in their interactions with Pαβ and αt*. In this study we intend to demonstrate that use of Pγ peptides as probes, in combination with a variety of techniques such as cross-linking, fluorescence spectroscopy, and site-directed mutagenesis, is a powerful method for studying Pγ interactions. © 1993 Academic Press, Inc.
Artemyev, NO; Skiba, NP; Mills, JS; Hamm, HE
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